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What is vesicoureteral reflux (VUR)?

Vesicoureteral reflux is the abnormal flow of urine from the bladder to the upper urinary tract. The urinary tract is the body’s drainage system for removing wastes and extra water. The urinary tract includes two kidneys, two ureters, a bladder, and a urethra. Blood flows through the kidneys, and the kidneys filter out wastes and extra water, making urine. The urine travels down two narrow tubes called the ureters. The urine is then stored in a balloonlike organ called the bladder. When the bladder empties, urine flows out of the body through a tube called the urethra at the bottom of the bladder.

In VUR, urine may flow back—reflux—into one or both ureters and, in some cases, to one or both kidneys. VUR that affects only one ureter and kidney is called unilateral reflux, and VUR that affects both ureters and kidneys is called bilateral reflux.

Who gets VUR?

Vesicoureteral reflux is more common in infants and young children, but older children and even adults can be affected. About 10 percent of children have VUR.1 Studies estimate that VUR occurs in about 32 percent of siblings of an affected child. This rate may be as low as 7 percent in older siblings and as high as 100 percent in identical twins. These findings indicate that VUR is an inherited condition.2

What are the types of VUR?

The two types of VUR are primary and secondary. Most cases of VUR are primary and typically affect only one ureter and kidney. With primary VUR, a child is born with a ureter that did not grow long enough during the child’s development in the womb. The valve formed by the ureter pressing against the bladder wall does not close properly, so
urine refluxes from the bladder to the ureter
and eventually to the kidney. This type of
VUR can get better or disappear as a child
gets older. As a child grows, the ureter gets
longer and function of the valve improves.

Secondary VUR occurs when a blockage
in the urinary tract causes an increase in
pressure and pushes urine back up into the
ureters. Children with secondary VUR often
have bilateral reflux. VUR caused by a physical
defect typically results from an abnormal
fold of tissue in the urethra that keeps urine
from flowing freely out of the bladder.

VUR is usually classified as grade I through
V, with grade I being the least severe and
grade V being the most severe.

What are the symptoms of
VUR?

In many cases, a child with VUR has no
symptoms. When symptoms are present,
the most common is a urinary tract infection
(UTI). VUR can lead to infection because
urine that remains in the child’s urinary
tract provides a place for bacteria to grow.
Studies estimate that 30 percent of children
and up to 70 percent of infants with a UTI
have VUR.2

What are the complications
of VUR?

When a child with VUR gets a UTI, bacteria
can move into the kidney and lead to scarring.
Scarring of the kidney can be associated
with high blood pressure and kidney
failure. However, most children with VUR
who get a UTI recover without long-term
complications.

How is VUR diagnosed?

The most common tests used to diagnose
VUR include

Voiding cystourethrogram (VCUG).
VCUG is an x-ray image of the bladder
and urethra taken during urination, also
called voiding. The bladder and urethra
are filled with a special dye, called
contrast medium, to make the urethra
clearly visible. The x-ray machine
captures a video of the contrast medium
when the child urinates. The procedure
is performed in a health care provider’s
office, outpatient center, or hospital
by an x-ray technician supervised by a
radiologist—a doctor who specializes in
medical imaging—who then interprets
the images. Anesthesia is not needed,
but sedation may be used for some children.
This test can show abnormalities
of the inside of the urethra and bladder.

Radionuclide cystogram (RNC). RNC
is a type of nuclear scan that involves
placing radioactive material into the
bladder. A scanner then detects the
radioactive material as the child urinates
or after the bladder is empty. The
procedure is performed in a health care
provider’s office, outpatient center, or
hospital by a specially trained technician,
and the images are interpreted by
a radiologist. Anesthesia is not needed,
but sedation may be used for some
children. RNC is more sensitive than
VCUG but does not provide as much
detail of the bladder anatomy.

Abdominal ultrasound. Ultrasound
uses a device, called a transducer, that
bounces safe, painless sound waves
off organs to create an image of their
structure. An abdominal ultrasound
can create images of the entire urinary
tract, including the kidneys and bladder.
The procedure is performed in a health
care provider’s office, outpatient center,
or hospital by a specially trained technician,
and the images are interpreted by
a radiologist; anesthesia is not needed.
Ultrasound may be used before VCUG
or RNC if the child’s family or health
care provider wants to avoid exposure to
x-ray radiation or radioactive material.

Testing is usually done on

infants diagnosed during pregnancy with
urine blockage affecting the kidneys

children younger than 5 years of age
with a UTI

children with a UTI and fever, called
febrile UTI, regardless of age

males with a UTI who are not sexually
active, regardless of age or fever

children with a family history of VUR,
including an affected sibling

For more information about urine blockage
in infants, see the National Kidney
and Urologic Diseases Information
Clearinghouse fact sheet Urine Blockage in
Newborns.

VUR is an unlikely cause of UTI in some
children, so these tests are not done until
other causes of UTI are ruled out for

What other tests do children
with VUR need?

Following diagnosis, children with VUR
should have a general medical evaluation
that includes blood pressure measurement,
as high blood pressure is an indicator
of kidney damage. If both kidneys are
affected, a child’s blood should be tested
for creatinine—a waste product of normal
muscle breakdown. Healthy kidneys remove
creatinine from the blood; when the kidneys
are damaged, creatinine builds up in
the blood. The urine may be tested for the
presence of protein and bacteria. Protein in
the urine is another indication of damaged
kidneys.

Children with VUR should also be assessed
for bladder/bowel dysfunction (BBD). BBD
symptoms include

having to urinate often or suddenly

long periods of time between bathroom
visits

daytime wetting

pain in the penis or perineum—the area
between the anus and genitals

posturing to prevent wetting

constipation—a condition in which a
child has fewer than two bowel movements
in a week; the bowel movements
may be painful

fecal incontinence—inability to hold
stool in the colon and rectum, which are
parts of the large intestine

Children who have VUR along with any
BBD symptoms are at greater risk of kidney
damage due to infection.

How is primary VUR
treated?

The standard treatment for primary VUR
has included prompt treatment of UTIs and
long-term use of antibiotics to prevent UTIs,
also called antimicrobial prophylaxis, until
VUR goes away on its own. Antibiotics are
bacteria-fighting medications. Surgery has
also been used in certain cases.

Several studies have raised questions about
long-term use of antibiotics for prevention of
UTIs. The studies found little or no effect
on prevention of kidney damage. Long-term
use may also make the child resistant to the
antibiotic, meaning the medication does not
work as well, and the child may be sicker longer
and may need to take medications that
are even stronger.

Current recommendations from the
American Urological Association include the
following:

children younger than 1 year of age—
continuous antibiotics should be used
if a child has a history of febrile UTI
or VUR grade III through V that was
identified through screening

children older than 1 year of age with
BBD—continuous antibiotics should be
used while BBD is being treated

children older than 1 year of age without
BBD—continuous antibiotics can
be used at the discretion of the health
care provider but is not automatically
recommended; however, UTIs should
be promptly treated

Surgery has traditionally been considered
for a child with kidney infection, fever, and
severe reflux that has not improved within
a year. However, some health care providers
recommend surgery when a scan of the
kidneys shows evidence of inflammation.
Several surgical approaches can be used
to alter the ureter and prevent urine from
refluxing.

Deflux, a gellike liquid containing complex
sugars, is an alternative to surgery for treatment
of VUR. A small amount of Deflux
is injected into the bladder wall near the
opening of the ureter. This injection creates
a bulge in the tissue that makes it harder for
urine to flow back up the ureter. The health
care provider uses a special tube to see inside
the bladder during the procedure. Deflux
injection is an outpatient procedure done
under general anesthesia, so the child can go
home the same day.

Children with VUR should also be
assessed for bladder/bowel dysfunction
(BBD). Children who have
VUR along with any BBD symptoms
are at greater risk of kidney
damage due to infection.

The standard treatment for primary
VUR has included prompt treatment
of UTIs and long-term use
of antibiotics to prevent UTIs, also
called antimicrobial prophylaxis,
until VUR goes away on its own.
Surgery has also been used in certain
cases.

Hope through Research

The National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK)
conducts and supports research to help people
with urologic diseases, including children.
The NIDDK’s Division of Kidney, Urologic,
and Hematologic Diseases (KUH) maintains
the Pediatric Urology Program, which supports
research into the early development
of the urinary tract. The KUH supports
several projects evaluating current treatments
for VUR, including the Randomized
Intervention for Children with Vesicoureteral
Reflux (RIVUR) to investigate whether prophylactic
antibiotic treatment prevents UTIs
and renal scarring in children with VUR.
More information about the RIVUR study,
funded under National Institutes of Health
clinical trial number NCT00405704, can be
found at www.cscc.unc.edu/rivur.

Participants in clinical trials can play a more
active role in their own health care, gain
access to new research treatments before
they are widely available, and help others
by contributing to medical research. For
information about current studies, visit
www.ClinicalTrials.gov.

Acknowledgments

Publications produced by the Clearinghouse
are carefully reviewed by both NIDDK scientists
and outside experts. This publication
was reviewed by Robert L. Chevalier, M.D.,
University of Virginia.

You may also find additional information about this topic by visiting MedlinePlus at www.medlineplus.gov.

This publication may contain information about medications. When prepared, this publication included the most current information available. For updates or for questions about any medications, contact the U.S. Food and Drug Administration toll-free at 1–888–INFO–FDA (1–888–463–6332) or visit www.fda.gov. Consult your health care provider for more information.

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The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Human Services. Established in 1987, the Clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic disorders and to their families, health care professionals, and the public. The NKUDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about kidney and urologic diseases.

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